The impact of agricultural land-use on soil microbial community composition and enzyme activity has not been extensively investigated in Ultisols. We investigated soil health parameters by analyzing phospholipid fatty acids (PLFAs), extracellular enzyme activity, C and N stocks, and soil structure. Four land uses were established in a tropical climate region of Brazil: native Cerrado (savanna), monoculture pasture [Urochloa brizantha (Hochst. Ex A. Rich.) R. Webster 'Marandu'], an integrated crop-livestock system (ICLS), and maize (Zea mays)-fallow in a no-tillage system. Soil microbial biomass was 40% higher in the native Cerrado than in the monoculture pasture, ICLS, and no-tillage maize. Soil organic carbon was positively correlated with microbial community composition (MB; gram–; AC; AMF; Fungi; F: B ratio) and enzyme activity (bG, AP, NAG). Large macroaggregates were positively correlated with bG, AP, and AMF. In summary, the native Cerrado had a higher level of carbon at the soil surface and greater soil structure with increased microbial biomass, gram+ bacteria, AMF, fungi, and F:B ratio in a tropical region of Brazil. However, bG and AP enzyme activities were lower in the ICLS and no-till maize at the soil surface (0–5 cm) compared to the native Cerrado. The conversion of native Cerrado to agricultural systems shifted the soil microbial community composition, enzyme activity, C and N, and soil structure of this sandy soil of the Brazilian Cerrado.

中文翻译：

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巴西热带气候区受土地利用和土壤深度影响的土壤微生物群落、酶活性、碳和氮储量和土壤聚集

农业土地利用对土壤微生物群落组成和酶活性的影响尚未在 Ultisol 中得到广泛研究。我们通过分析磷脂脂肪酸 (PLFA)、细胞外酶活性、碳和氮储备以及土壤结构来研究土壤健康参数。在巴西的热带气候区建立了四种土地用途：本地塞拉多（热带稀树草原）、单一栽培牧场 [Urochloa brizantha (Hochst. Ex A. Rich.) R. Webster 'Marandu']、综合作物 - 牲畜系统 (ICLS)和玉米（Zea mays）——在免耕系统中休耕。本地塞拉多的土壤微生物生物量比单一栽培牧场、ICLS 和免耕玉米高 40%。土壤有机碳与微生物群落组成（MB；gram–；AC；AMF；Fungi；F:B 比）和酶活性（bG、AP、唠叨）。大团聚体与 bG、AP 和 AMF 呈正相关。总之，在巴西热带地区，原生塞拉多的土壤表面碳含量更高，土壤结构更大，微生物生物量、革兰氏菌+细菌、AMF、真菌和 F:B 比率增加。然而，与天然 Cerrado 相比，ICLS 和土壤表面（0-5 厘米）免耕玉米中的 bG 和 AP 酶活性较低。本地塞拉多向农业系统的转变改变了巴西塞拉多这种沙质土壤的土壤微生物群落组成、酶活性、碳和氮以及土壤结构。革兰氏阳性菌、AMF、真菌和巴西热带地区的 F:B 比例。然而，与天然 Cerrado 相比，ICLS 和土壤表面（0-5 厘米）免耕玉米中的 bG 和 AP 酶活性较低。本地塞拉多向农业系统的转变改变了巴西塞拉多这种沙质土壤的土壤微生物群落组成、酶活性、碳和氮以及土壤结构。革兰氏阳性菌、AMF、真菌和巴西热带地区的 F:B 比例。然而，与天然 Cerrado 相比，ICLS 和土壤表面（0-5 厘米）免耕玉米中的 bG 和 AP 酶活性较低。本地塞拉多向农业系统的转变改变了巴西塞拉多这种沙质土壤的土壤微生物群落组成、酶活性、碳和氮以及土壤结构。